Microscopic Description -- A 7 year old boy with massive splenomegaly


The peripheral blood (image 1) shows anisocytosis, macrocytosis, hypochromia and decreased platelets. The bone marrow aspirate shows complete erythroid and myeloid maturation (image 2). Megakaryocytes are present in normal numbers. Individual as well as large clusters and aggregates of macrophages with eccentric nuclei, abundant blue-gray cytoplasm and wrinkled tissue paper appearance are seen (images 3, 4, 5). The bone marrow biopsy (images 6, 7, 8) is 90% cellular, which is normocellular for the patient's age. Large cells with abundant lightly eosinophilic, fibrillary cytoplasm infiltrate the bone marrow in sheets, clusters and as individual cells.


Iron stain (image 9) is positive in the macrophages. No ringed sideroblasts are present. The macrophages are also positive for PAS (image 10). Because PAS stains glycogen and mucopolysaccharides, it highlights glycolipids, such as glucocerebroside (which accumulates in Gaucher disease). It will not stain materials that do not contain glycol groups (or their derivatives), such as sphingomyelin, a phospholipid which accumulates in Niemann-Pick disease. CD68 (image 11) immunostain specifically reacts with lysosomes. It does not stain antigen presenting cells, but is positive in macrophages located in many tissues. It is used as a marker for histiocytes, and confirms the macrophage lineage of the large cells described above.


Flow cytometric immunophenotypic studies performed on the bone marrow revealed polyclonal B cells, heterogeneous T cells, and a small population of hematogones.


Normal male karyotype, 46,XY.


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